


Knot Quite The Plan

by NihilismPastry



Series: Laced and Bound [3]
Category: Undertale (Video Game)
Genre: Animalistic Sans, BDSM, Bara Sans, Bara!Sans, Beast Tale, Beasttale AU, Big Sans, Biting, Blood, Dirty Talk, Dom!Sans, Ecto-Penis, Ecto-Tongue, Ecto-dick, F/M, Female Reader, Fluff, Knot kink, Magical appendages, Nipple Play, Papyrus is a cinnamon roll, Part of a one shot collection, Primal Sans, Reader Is Not Frisk, Rough Sex, Small reader, knotting kink
Language: English
Status: Completed
Published: 2016-08-26
Updated: 2016-08-26
Packaged: 2018-08-11 03:23:06
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,548
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7874251
Author URL: https://archiveofourown.org/users/NihilismPastry/pseuds/NihilismPastry
Summary: <blockquote class="userstuff">
              <p>Sans has been working way more than usual, thankfully his mate is pretty understanding.</p>
            </blockquote>





	Knot Quite The Plan

**Author's Note:**

> Hello everyone. Welcome to the third one shot in the Laced and Bound One-Shot Collection. This is set in the Beast Tale AU, made by Get Rammed on Tumblr, here's a link for those who are unfamiliar with it. http://get-rammed.tumblr.com/ You don't really have to know it if you read these, but some physical characteristics will be confusing if you at least don't see a picture of this Sans. Anyway, I hope you all enjoy.

The summer season was officially a busy season. With the lack of rain, Sans had to put more hours into the mine that he worked at. On a daily average he probably saw the sun for the five minutes it took him to get dressed, before he took a shortcut to his job. By the time he got back home it was well past midnight, and the house was always dead silent. In fact he hadn't had a day off since the beach three weeks ago. He almost wished it was time for his heat, just so he could get away from the dank cave he called his job.

He fell through the void and into his and his brother's bathroom. It was after another long shift at work, and he knew it was late. He couldn't hear his mate and brother watching TV, or messing around in their rooms. The only sound was the fans whirring on the ceilings. He quickly stripped of his clothes and got in the shower, turning the water to its coldest setting. He then grabbed a stiff brush and scrubbed the oil and chemicals off his bones. The water became a murky brown color, and he knew it would stain the tub. He made a mental note to at least spray some cleaner in it before getting out of the shower.He opened the bottom cabinet and took out a pair of black shorts. Without bothering to dry off, he pulled them on and left the bathroom. It was time for his nightly rounds.

He went down the hall and stopped outside an exceedingly large door with posters and stickers on the outside. He reached up for the door knob, and carefully opened the door. All of the lights were out, and a cool breeze circulated through the room. In the corner was a simple four poster bed with a gigantic lump in it. The skeleton padded across the carpet and to the bed, peeking at his little brother. There wasn't a hint of distress on his skull, and he was clutching his phone. He tapped a button on the screen, and a series of messages popped up. Looked like he fell asleep talking to his 'kitten' again. He slipped the blocky phone from his brother's grip and put it on the charger. Once that was done he pulled the blankets over Papyrus's broad shoulders and pat his skull.

One down one more to go.

He padded out of his brother's room, and went to a much smaller door across from Papyrus's room. This door was slightly open, and he could hear snoring. He opened the door a bit wider, and slipped into the room, being sure to close the door behind him. He picked his way across the piles of dirty clothes and trash. When he made it to the bed, he found his mate curled around a pillow, and the blankets on the floor. She was just wearing her underwear and a tank top, something else she rarely did. He crawled into the bed next to her, and wrapped his arms around her waist. She moaned and her breathing shifted, she was awake. "Sans?"

"I'm here, baby girl."

His mate sighed and rolled over, eyes narrowed as she tried to keep them open. "Did you just get off?"

"Are ya offering?" He chuckled at the obnoxious sigh and eye roll. "Nah, I just got off work a few minutes ago. Don't worry 'bout it and sleep."

She hummed and nuzzled closer to him, her arms reached up and encircled themselves around his neck. "Night."

"Night, baby girl."

* * *

 

The next day Sans got a call that there was some type of gas leak in the mine, so they were shutting it down for the day. This impromptu day off was celebrated by sleeping in until noon. He didn't even consider leaving the bed until his brother called him downstairs to at least eat something.

He threw a shirt over his head and shuffled into the kitchen. His mate was at her usual spot on the counter, while Papyrus was stirring a pot. From the tangy smell, he had to guess it was tomato sauce. "THERE YOU ARE, LAZY BONES. YOUR HUMAN AND I HAVE ALREADY PREPARED SOME LUNCH."

"Thanks, bro."

He swiped his human off the counter as he passed by. She shrieked and grabbed a hold of his shoulders, her face buried into his neck. "You're so clingy today."

He just grunted and pressed his fangs to the top of her head before setting her on the table. Thanks to everything in the house being huge, his mate usually just sat on all the tabletops, it made life easier. Sans sat in a chair in front of her and watched as Papyrus laddled some food on two large plates, then a much smaller one. He handed Sans's mate the smaller plate, before passing Sans his own.

The three began to dig in their food, while the human and Papyrus chatted a bit. Apparently Toriel and Frisk had been over yesterday, and Frisk had showed Papyrus a new game they had learned from their foster mother. Something to do with traffic lights and colors. Toriel had finally managed to find a lawyer to represent her in court, and had invited everyone to a party set for next week. The lawyer was almost certain that he could get the court to give Frisk back to Toriel.

As they finished up the meal, his mate leaned forward. "Hey, I've got something I wanna do with you today."

This was usually the part where he would suggest sex, but Papyrus was sitting right across from them. "What's that?"

"It's a surprise~." She set her empty plate to the side. "Paps helped me with it though, so it's bound to be awesome."

Papyrus nodded. "OF COURSE IT'S AWESOME, HUMAN. THE GREAT PAPYRUS HELPED YOU WITH THE PROJECT." He suddenly gasped and shoveled more food into his mouth. "AS MUCH AS I WOULD LIKE TO SEE THE RESULTS, I MUST BE GOING. I PROMISED KITTEN I WOULD WALK HER HOME FROM THE DOCTOR TODAY."

Sans glanced back to the clock on the stove. It was ten until one, she must be getting out by two. Papyrus was ten minutes early to every place he went. Though, Sans did wish his brother could hang out today. He didn't know the next time he'd have a full day off. "Stay safe, bro."

"You'll have to bring 'Kitten' home some time." His mate said. "I'm kinda curious about what she's like."

 Papyrus's skull flushed a pale orange. "I...Shall consider this, human." He pushed himself up and put his plate in the sink. "I AM OFF BROTHER, HUMAN! DO NOT HAVE TOO MUCH FUN WITHOUT ME!"

"Can't do it without ya bro. Your personality is a real _rib_ tickler."

Papyrus groaned and shook his head. "AND HERE I THOUGHT I THOUGHT I WAS HAVING A PERFECT DAY, APPRENTLY IT WAS A...FIBULA."

Sans burst into laughter while his brother muttered it wasn't that funny before storming off. Sans's chuckles began to die, leaving him with a warm buzz in his bones. He caught his mate's stare, a small smile on her face. "What?"

"You both are so cute."

His magic crackled and he felt his face go warm. He looked away and wished he had his jacket to cover his face. He was a damn near eight foot monster, he wasn't cute! "Shut up."

She just giggled and slid off the table. "Come on cutie, time for your surprise~!"

* * *

 

The surprise ended up being a nest of blankets and pillows, arranged in some kind of lopsided cube like hideaway, in the middle of his mate's room. She dragged him over to it, a small smile on her face. "I know you're usually in cramped spaces all day, but Papyrus and I made one last week, so I thought you'd like to hang out in one too." Well this explained why she bunked in his bed last night. He watched his mate pull back a blanket so he could slid inside. "Just watch your tail."

He bent down and crawled into the space, purposely flicking his tail at his mate's legs. She yelped, but didn't complain. The inside was a mess of pillows, most of them laid out in a crooked half circle. A small stack of books were in a corner, along with a bag of ketchup chips. He went to the far wall and laid out on his side, being g sure to give his mate plenty of room when she slid in. "So whadda ya do in these things?"

"Well, Papyrus and I did some crossword puzzles," She said as she said as she leaned against his rib cage, her legs stretched out in front of her. "and my brothers used to play cards or board games." She shrugged. "Guess it depends on what you want to do."

His arms circled around her waist, drawing her close. "Well I'm gonna take a nap. Been awhile since I've done that with ya."

She hummed and caressed his skull with a hand. He leaned into her touch as he closed his sockets. His nap flew by fairly quickly, by the time he woke up again his mate had left. He slowly sat up and blinked the sleep out of his sockets. How long had he been out? He fished his phone out of his pocket and turned it on. Huh, only four o'clock. His mate must have gotten hungry and gotten something. 

The warm smell of cheese wafted into the room, along with something sweet. A tray slipped through the fort opening, followed by his mate. She sat on her knees and set the tray between the two of them. "I was gonna wake you up, guess great minds think alike." She picked up one of pizza slices off the tray. "Hungry?"

Sans picked up a three meat slice and downed it in one bite. He ignored his mate's eye roll and picked up another. The meal was eaten in comfortable silence, it wasn't until they started on the cookies that he spoke again. "With me workin' all the time, do ya feel a change in your soul?"

"You worked a lot before," His mate said. "if there is a difference I don't feel it. Definitely doesn't affect my magic, I still suck at it." She picked up another chocolate cookie. "Why, is it affecting you?"

Aside from anxiety, no. However he brushed that aside as reached out and pulled down the yellow shot she wore. The cube like mark for her soul barrier looked relatively untouched. The pale lines gently pulsed as it processed his magic, but there was nothing out of the ordinary once the last time he checked. "I'm given ya my magic now, I can give ya more if you're close to me. If I'm gone and tired all the time, then you'll end up dying cause I'm not there to give it to ya." His grip on her shirt tightened. "I'm not 'bout to kill my own mate through magic deprivation. Not when I can prevent it."

She stared at him for a moment before she clambered over the tray of food. A growl rumbled through his ribs, and his magic sparked as she straddled his lap. He could feel the heat her body gave off through her shorts, and just how damn squishy she was over all. Her fingers ghosted over his cheekbones as she reached up and kissed him. Her lips were soft against his teeth, so malleable but slightly chapped. His hands gripped her waist, putting enough pressure that he knew she'd get bruises. A soft tongue flicked out and met his own slimy one. His curled around hers, and with a sharp tug he began to suck on it.

Really, it was hard to believe that they were forced into this situation. Sans had to admit, he'd come to really care for her in the last six months. It was no longer about being able to keep Papyrus in a safe place, but being able to keep both Papyrus _and_ his mate safe, loved, and happy. And if that meant working shitty hours at the mine, then so be it. 

His mate pulled back from the kiss, a trail of glowing saliva keeping them connected. He growled and grinded his very obvious bulge against her clothed cunt. She mewled and kissed him again, this time harder, and her fingers going under his shirt to trail down his ribs. He yanked on her shirt and hiked it up, separating their mouths long enough to get it off. Huh, she was going without a bra. He grabbed one of her tits and squeezed it. "Ya little slut."

"More like, I just didn't want to wear a bra."

He ignored her as he bent his head down to lick at her shoulder. He ghosted lower to her sternum down to her tits. His tongue curled around the left nipple, and he squeezed it the best he could while his hand rolled and pinched the right one. She ground her body down on his hard on, a moan escaping her lips. He growled and kissed her again, bucking his hips into her. He could hear her breath quicken, feel her heart pound against her chest, and smell her arousal. It clung to skin and every time she shifted another burst of it filled his senses. His hands slipped back to her waist and he forced her to sit deeper on his pelvis. He growled again and his hips rutted against hers. " _Fuck_ , baby girl."

His tongue reached out from her mouth and slid down her neck and shoulder. She tasted like salt and cream, if this was the result of new soap he could really get used to this taste. Better than a raspberry chemical cocktail. He constricted his arms around her waist waist and bit down into her shoulder. It was deep and satisfying, blood welled to the surface and slid down her skin and onto the blankets. Her voice rose an octave and her grip on his ribs tightened. 

"Ya taste **so fucking good** , ya know that?" He licked away the excess blood, leaving bloody streaks across her skin. "Your blood drives me crazy."

She rolled her eyes and opened her mouth, but was cut off when his mouth found her's again. He shoved his tongue in, letting her taste some of her blood. While she was busy sucking his tongue, he pushed her shorts to the side and slid one of his claws into her pussy. She was already wet for him, and as he pumped his finger, she tried to grind against it. 

"Master-Ah," He slipped another claw into her opening. "can we fuck in this position?"

"Ya wanna keep your hiding place up?"

She nodded, her blush becoming darker. Whether it was thanks to his fingering or actual embarrassment he wasn't sure. "Alright, baby girl. Besides, ya can take my cock and knot in any position, can't ya?"

She nodded again, her hold on words going the faster her pumped into her. Juices flowed down his fingers and her breathing was loud. She was so close, he could practically hear her muscles tighten around him. Just when she was at that point, her toes curled and moans turned to pleads, he ripped his fingers out of her and wrapped his tongue around them. He smirked as he watched her stare at him with wide eyes, but didn't complain. 

He released his fingers and stripped off his shirt. "Ya know why I'm denying ya that orgasm, baby girl?" She shook her head. "It's because I want my cock deep in your pussy when that happens. When you finally cum, **I wanna feel it**." He smacked her ass and she scrambled off of him long enough for them both to take off their shorts before she was straddling him again. His bright green and yellow cock was already at full mast in front of her pussy, and he couldn't wait to ram it in her. "I haven't had an orgasm in weeks, so this'll be a long time heh, _cumming_."

"You're so lucky I'm horny, master."

He pressed his cock at her entrance, the tip pushing open her lips and stretching her just a bit. God he wanted to just fuck her, but this was the first time she'd taken him in nearly a month. While any other time he knew she could take it, he didn't want to accidentally rip her apart just because he was impatient. She slowly was eased onto his length, quiet whimpers escaping her lips the closer she got to his base. "Good girl, you've almost got it. Just a little more, baby."

He glanced down at her stomach and smirked. He could see the indent his dick made in her body. It made him growl and his hips shifted, making her take the final inch or so. She hissed and grabbed his shoulders, mouth screwed up in concentration. "G-give me a second, master."

She'd said those words the first time they fucked. Hell, it had even been in a similar position since she was afraid to let him completely dominate her. Four months had really passed by, hadn't they? He leaned down and nuzzled his nasal cavity into her neck and nipped at her shoulder. Her breath hitched and she tilted her head to the side, exposing her bite marked neck to him. "You're a total maschocist, aren't ya, baby girl?"

"Only for you, master."

"Damn straight."

He slowly sunk his teeth into her neck. It was the same wound as earlier, so blood didn't gush out all over the place, but it still felt amazing. Her back arched into him, pressing her tits into his ribs. "Master."

He released her neck. "What is it, baby girl?"

Her muscles flexed and she pulled herself a few inches up his cock. She pressed her mouth where his ear would be. "Please fuck me, I'm ready now. I need it, master."

Normally he loved the begging game, but it had been so damn long. He growled and began at a hard pace, putting into her with deep yet slow strokes. He wanted to feel every inch of her pussy, remind her that he owned her, that he hadn't forgotten this fact during his time at work. "Dammit, ya feel so good. Do ya know how much I think about ya, baby girl? When I get home all I wanna do is fuck this tight pussy into oblivion. To force my knot inside ya and just cum until ya finally wake up, **then do it all over again**."

She gasped and clawed at his ribs, her fingers trailing upwards to bring his skull to her so she could kiss him again. This time is was sloppy, he bit her lips and she practically inhaled his tongue once it got inside her mouth. His pace was faster now, she was so close, he could feel the muscles tightening around him. "Cum for me, baby girl."

Her back arched and she brought her hips down, trying to take him all in as her inner muscles squeezed him. Her mouth was open and a wail tore through her throat as the orgasm ripped through her. He didn't stop though, his pace remained fast and hard as his mate orgasmed. He leaned down and nibbled on her neck, small puncture wounds peppered the area, the blood only serving to spur him on. "Fuck, baby girl." He lapped at her neck, drool dripping down her neck and between her breasts. "Say my name."

"S-Sans!" She was on the verge of her second orgasm. "Oh god, Sans! I'm so close-"

"I know." He licked her ear. " **Cum, scream my name**." 

She did exactly that, head thrown back and arms curled around his neck as she held him as close as she could. Her body writhe and shuddered against his own, her muscles clamped down on him. He forced her down hard, getting all of his cock and his knot inside her. Cum spurt into her cunt with a growl of her name, and her blood on his tongue. They remained like that for a few moments, the initial orgasm making their bodies sensitive to all movement. Once he was on spurt six, Sans held his mate close and laid down with her, being sure not to jostle her too hard since he was tied to her.

His mate moaned and buried her head into his neck. "That was not in the plan."

"Huh?"

"I was gonna try to romance you and stuff first, then have sex later. You were like, ten steps ahead of me or something." She lightly smacked his ribs. "Jerk."

He just grunted, another wave of cum bursting from his cock and into his mate. "Well, it was worth it. Should be proud of yourself, baby girl. Nothin' better than a nap, some good food, and hot sex."

She rolled her eyes. "I can think of a hundred things better than all three of those."

"Yeah?"

"Chocolate." 

"Keep dreamin', baby girl."

 

**Author's Note:**

> I actually liked how this chapter turned out. It was the perfect balance of fluffy and sex, which I love. 
> 
> So, for those of you who are knew to my one-shots. The story is rolling in the background, and nothing is outright explained. So Frisk is in foster care, and Toriel is trying to win them back. Sans and 'Baby Girl' are already soul mates, but it wasn't by choice, and Payrus is dating some random female neither of his house mate's have met. You didn't miss anything, I just love adding an already active story, but reading the other two one shots would make me happy. 
> 
> Checking out my tumblr would also make me happy? http://nihilismpastry.tumblr.com
> 
> So uh, that's it I guess.


End file.
